Organic materials exposed to ultraviolet (UV) light undergo degradation, which may change their chemical composition and structure, mechanical properties, surface appearance, and color. This UV aging is associated with natural weathering of plastics, coatings, adhesives, waxes and other special materials exposed to exterior and some interior conditions. Natural and synthetic dyes lose their color and undergo fading when exposed to short wavelength light as well. Natural weathering of materials is a complex process where UV light interaction with matter plays a significant role but may not be the only factor. There are other factors associated with aging of materials containing organic compounds, for example heat or exposure to acidic conditions in the form of acid rain or air contaminants such as sulfur dioxide, etc.